Police are warning ATM users to be vigilant after cash traps were found in the city.
The devices, which can swallow cash and cards, were found at Barclays Banks in Lincoln and Boston at the end of May and the beginning of June.
It has sparked a warning from Lincolnshire Police, which has been offering advice to residents.
Chief inspector Simon Skelton said: “We would ask residents to remain vigilant when using cash machines.
“If you see anything unusual about the cash machine or it looks like it has been tampered with, don’t use it and report it to the bank as soon as possible.
“If an ATM swallows your cash card for any reason, report it to your card company straight away, ideally using your mobile while you’re still in front of the machine.”
Anyone who notices anything suspicious is being urged to call 101 or 999 in an emergency.